The Bulldogs, toppled by Dawn Staley's South Carolina squad in the Southeastern Conference Tournament title game, finished the season at 20-12.
Shields, who came into the game averaging 14.9 points, had a game-high 18, connecting on seven of 16 from the floor and four of six from three-point range.
Hawks junior guard Natasha Cloud, from Cardinal O'Hara, added 13 points and junior forward Ashley Robinson, of Archbishop Wood, finished with 10 points and 10 boards.
Georgia began the second half trailing by eight points but rallied and briefly led, 49-48, on a three-pointer by Tiaria Griffin with 10 minutes left.
The Hawks answered with a 9-0 scoring run and kept the Bulldogs in check the rest of the way.
"We just weren't doing the little things to get open, and when you're playing such a great defensive team like Georgia, they try to take the first and second pass away," said Hawks coach Cindy Griffin. "If we can get past those first two passes, we're going to be able to get some open looks, and we did that."
St. Joe's defensive presence stiffened, however, and the combination of Robinson's diligence under the glass, and Cloud's offensive qualities, came to the forefront.
"I think my teammates having confidence in me, [which] really gives me a boost," Cloud said of her second-half effort, which produced nine points and an assist. "At that point, coach had dug into me a little bit, telling me to shoot the ball, so I did. We made plays and we got open looks. We executed very well in the last minutes."
The Bulldogs enjoyed a brief 5-4 lead after Krista Donald's tip-in 3:26 into the game. Moments later, Shields connected on a long three giving the advantage back to the Hawks. But the Bulldogs, who committed 10 turnovers and shot just 35.3 percent from the field in the first half, refused to roll over.
The Hawks led by as many as 10 points midway through the half, before the persistent Bulldogs used a 16-9 run to pull to within 33-30, courtesy of an Erika Ford jumper with 2:12 left.
With 57 seconds before intermission, the Cloud scored on a drive and was fouled by Merritt Hempe. Cloud's free throw and Sarah Fairbanks' midrange jumper with 17 seconds to go pushed the Hawks to a 38-30 halftime edge.
"Coming in, coach had said that I had to be ready to shoot and it's really important that I can't worry about the last play or last missed shot," said Shields, who led the team in scoring for the 13th time this season. "Having teammates pick you up, and coaches telling you to keep pushing was the difference."
In the midst of postgame analysis, Griffin spoke of the significance of her club's win.
"It's terrific," she said. "Not only is it great for Saint Joseph's University and our program, but it's also great for the Atlantic 10 Conference. I
"It's a steppingstone, and though we were very excited about winning the Atlantic 10 Tournament last year, this team wanted to take it a step further this year in getting to the tournament and winning a game. It's huge."